Abstract:
Objective To solve the frequent wellbore and surface blockage of the Dengying Formation gas wells in the Gaoshiti-Moxi (Gao-Mo) block.
Method The compositions of the blockage were analyzed using the X-ray diffraction analyzer and the plasma spectrometer. Based on the analysis results and the synergistic effect, a targeted blockage removal fluid was developed, which mainly consists of organic acid chelating agents, organic amines, polyethers, and is supplemented with corrosion inhibitors, surfactants, and other additives.
Result The blockage was mainly composed of FeS, FeS2 and S, with a small amount of organic components such as esters, organic acids. The solubilization rate of the fluid for the blockage at 80 ℃ could reach 69 g/L. The average corrosion rates of L360 and nickel alloy 825 steel plates were 0.033 1 mm/a and 0.002 1 mm/a, respectively. The swelling rate of the sealing materials was between 0.9% and 1.1%.
Conclusion The blockage removal fluid has a good dissolution effect on the on-site blockage, and has lower corrosivity and lower swelling to on-site metal and sealing materials. It is suitable for the unblocking process of well shut-in soaking and well opening drainage. It has been successfully applied in 51 wells in the Gao-Mo block, and the unblocking efficiency was calculated to be 84.31% based on the oil pressure and daily gas production before and after the measures, ensuring the stable production of the Dengying Formation gas wells in the Gao-Mo block.
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